Present methods of cleaning carpets, and compositions appropriately suited therefor, include:
1. Aerosol Foams: Typical products are based on surfactant/solvent blends which, by means of gaseous propellants, blow into stiff, dry foams which adhere to the upper surface of carpet fibers but, owing to the relatively dry, high density foam, are incapable of independently penetrating the carpet fibers. Thus, these foams must be driven into carpet fabric piles with wet sponge or other type mops. Thereafter, in order to separate the soil from the carpet fabric, vigorous, and sometimes exhaustive, abrading of the carpet fibers with a brush must be accomplished.
Disadvantages of foam aerosols are apparent. Aside from sometimes arduous efforts required to drive such a cleaner into the carpet fabric, such aerosol foams actually remove relatively little soiling material from carpet fabric. Furthermore, if one seeks to improve the emulsifying effects of the foam aerosol by adding more water, either directly, or via the sponge mop, it appears the only results are the deleterious ones of thoroughly wetting the carpet backing, thus necessitating the need to dry out the carpet fibers over a longer period of time, and further driving the foam aerosol composition itself into the fibers. Whether this type of cleaner is used with water or not, a tacky residue may be left on the surface of the carpet fibers. This then promotes re-soiling of the carpet fibers. The result is that if such a carpet fabric surface is cleaned with aerosol foams, the more often it must be re-cleaned.
The only apparent advantage that foam aerosols have is that they are relatively inexpensive and require no special equipment. However, economic benefits of these cleaners are obviously severely mitigated due to the re-soiling phenomenon.
2. Rotary Brush Systems: This system usually requires professional machinery, generally speaking brushes mounted on a rotary drum which is driven by a motor housed in an upright, broom-like appliance. This system is actually nothing more than a more effective way of driving in a cleaner such as the aforementioned foam cleaners into carpet fabric piles. Because of the motor-driven action, this particular system is extremely wearing upon thick, pile and shag-type carpets. Many of the fibers are abraded out of the fabric of the carpet, and thus, upon drying, the carpet does not "fluff" as readily as before. Eventually, the life of the carpet may be decreased by the abrasive action of such cleaners. Further, previously expressed disadvantages of increased wetting, longer drying time and relatively inefficient cleaning, are lessened, but, in view of the cost, and special equipment that need to be used in this system, such system is not significantly better than cleaning with aerosol foams. Furthermore, even with the rotary brush system, there is significant re-soiling.
3. "Steam Extraction": Although nominally called a "steam extraction" system, this type of cleaner does not utilize steam, but rather pressurized, heated water in combination with surfactants and other cleaning agents. In practice, the surfactant and other agents are dissolved in a solution of hot water, then injected directly into the carpet fabric via a pressurized delivery system. The surfactants wet the carpet fabric pile, however, the hot water also aids in the penetration of the carpet fabric and in the emulsification of soiling agents and particles, as normally higher temperatures will cause an increase in surface wetting abilities of a given surfactant composition. After the surfactant solution has had sufficient time to emulsify and loosen soiling particles in the carpet fabric, it (and the water associated therewith) are physically removed from the carpet pile by means of the powerful vacuuming system generally available with this "steam extraction" system. Thus, problems of drying are generally avoided by the physical removal of the water and surfactant solution by the vacuum. However, unless the carpet is then "rinsed" with clear water solutions and re-vacuumed, resoiling may again occur because the carpet has a tacky residue.
The major, apparent disadvantages of such a "steam extraction" system are the expenses of renting the "steam extraction" system, and purchasing the chemicals needed therefor. Furthermore, it is inconvenient for the ordinary consumer to have to go to the local supermarket or hardware store to obtain these items.
Professional cleaners may utilize either this system or the prior, rotary brush system. By using professional cleaners, even more expense is added.